Congenital calvarial defects are a group of disorders characterized by congenital calvarial bone defects that vary in severity.
Radiographic features
CT with 3D shaded surface reformats is the best imaging tool as it demonstrates calvarial defects and bone margins:
- parietal foramina
- parietal fissure: small residual incomplete medial parietal bone suture
- sinus pericranii: communication between intra- and extra-cranial venous systems through calvarial defects
- arachnoid granulations: often multiple having irregular contour
- atretic cephalocele
- abnormally large fontanelle: secondary to increased intracranial pressure or skeletal dysplasia
- aplasia cutis congenita: congenital skin defect which may have underlying skull defect
- cleidocranial dysplasia: enlarged sagittal and metopic sutures, wide anterior and posterior fontanelles, broad cranial diameter, multiple Wormian bones along lambdoid sutures
- cranium bifidum occultum (cleft skull): delayed ossification of parietal bones with subsequent large midline skull defect
- amniotic band syndrome: large skull defects
- acalvaria: absent superior osseous cranial vault and dura matter. Normal skull base, brain and facial bones.
- acrania: partial or complete absence of cranial vault bones with abnormal cerebral hemisphere development.
Differential diagnosis
Imaging differential considerations include:
- lacunar skull
- calvarial epidermoid/dermoid
- calvarial hemangioma
- calvarial Langerhans cell histocytosis
- calvarial metastasis